Generally, stereophonic sound reproduction systems involve two speakers connected to audio signal sources derived from recordings of multi-frequency sound of common origin generated externally of the system at spaced locations in a sound radiation listening zone. In this manner, an attempt is made to simulate the differences in pressure, time and phase of the sound pickup by the left and right ears of a listener in a sound radiation listening zone. Although two stereophonic speakers are generally driven by separate audio signals which differ from each other with respect to the aforementioned sound characteristics to create a more realistic perception of sound as compared to monaural systems, a faithfully complete reproduction of the sounds is not possible because the sound radiation pattern within the listening zone is not taken into account.
In an effort to improve the impression of realism, an increase in the number of speakers has been proposed, such as four speakers in a quadrophonic system. In such a system, the two dimensional nature of the stereophonic system is enlarged to a three dimensional system. Such enlargements of the basic stereophonic system not only introduce complexities with respect to differences in the signals fed to each of the speakers, but also create an artificial volumetric zone within which the listener is to be confined. Other multi-speaker systems involve the creation of various artificial sound effects, including the introduction of acoustical delays and polar effects.
It is, therefore, an important object of the present invention to provide an improved stereophonic sound reproduction system which will more completely and effectively utilize the recorded stereophonic information without introducing any artificial effects or establishing any artificial zonal limits.
Another object of the present invention is to provide a stereophonic reproduction system which will more faithfully simulate the location of a listener within the audience zone associated with the sounds being recorded.